1. Field of the Invention
This invention relates to apparatus used to screw together (or “make up”) and unscrew (or “break out”) threaded tubular connections joining sections (frequently called “joints”) of tubulars, frequently (but not exclusively) used in the drilling of oil and gas wells. Such apparatus are commonly referred to as tong units.
2. Related Art
Tong units are used to screw together (or “make up”) and unscrew (or “break out”) threaded tubular connections joining sections (frequently called “joints”) of tubulars. Such tubulars are frequently used in the drilling, servicing and completion of oil and gas wells, in the form of drill pipe, tubing, and other similar tubular goods. Such apparatus are commonly referred to as “tong units” or “power tongs,” which use toothed dies carried by tong jaws, to transmit torque to the tubular connection. It is to be understood that the term tong unit, for purposes of this application, encompasses both the portion of the tong unit commonly referred to as the power tong portion of the tong unit (that is, the part that turns one side of the tubular connection) and the portion of the tong unit commonly referred to as the backup portion of the tong unit (that is, the part which holds the other side of the tubular connection).
In more detail, this invention relates to a tong unit which comprises an upper cage plate having a removable window section therein, as more particularly described herein.